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Paul MontgomeryFlag for United States of America

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System randomly locks up...

Hi all.
My system randomly locks up on a daily basis. What's wrong? Just kidding. I know this is a tough one. Actually it does  do this on a daily basis. Here's what I have tried. I did a system restore back to a point before it started happening. No luck there. I tried to uninstall anything that runs in the background at random times (Diskeeper, Norton AV ect...). I have 2 hd's in the box. One has XP on it and the other has 2000. So I have my choice when booting up. I have booted into  both OS's and it still happens in either os so I'm thinking that would eliminate the hd's as the problem (not to mention I've run a disk checker on both. Bad ram is my next suspicion. In any case, what else should I be looking for? How can you test a dimm to see if it's the problem (no I don't have a different one to put in in it's place).
System specs:
System board: DFI Lanparty Ultra II
Proc: AMD Athlon XP 2800+
Ram: 512 DDR matched to mobo from Crucial (can't remember the rest of the details)
2 hd's: 1 Maxtor 80 gig 7200 and another Maxtor 20 gig 7200 (both EIDE)

I hope I'm remembering to include everything...

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There are many software memory testers that work well to excercise the memory to locate a defect. Try downloading memtest86 from and run it. Otherwise, you need to find a known good stick of memory to use or find a local shop that has a memory tester. Is there any pattern to the system freezes (duration, performing particular operations, time of day, etc). When this happens have you noticed the cpu heat sink to be very hot? Can you strip everything out of the system but the video card and the W2k HD and eliminate the possibility of device conflict? Is the heat sink on the video card very hot. Does your memory have a heat spreader on it (metal shield)? Are you overclocking? Go into your BIOS and return your settings to factory defaults (usw, press DEL, F1, F2, on power on when you see the initial screen). You can also clear the BIOS completely by shorting the onboard jumper near the battery (usw, normal is 1-2 and discharge 2-3). During this process of elimination disconnect external peripherals. Let us know what happens.  mike
You may want to open the pc and clean all of the dust out of it.
A dusty pc will over heat and can cause it to lock up also.
Try running the pc with the side panel off and with a fan blowing into it to check for a over heat problem.
Other things that can cause a lock up.
1) Ram already coverd by mlynch24
2) Weak or falling power supply.
3)Failing video card

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In addition to the above, a failing IDE controller or cable could cause random lockups.  Swap the cable and change the channel the cable is attached to.
Avatar of Paul Montgomery


Snowguy - Power supply is 400w and about 3 months old so things should be fine there. The box has 2 fans on the PS, 1 fan in the side of the case and has quite a bit of ventilation. I opened it and it was warm inside but not hot by any means. The proc fan has a large heat sink under it and is working fine. Just barely warm. The vid card is a Ge Force 3 Ti 500. It's pretty warm to the touch but the fan is working fine on it. There was very little dust in the case but I blew it out anyway. I usually do that regularly anyway.

Mike - I'll try the memory tester. As far as  a pattern goes it seems very random. The first time it happened it was overnight sometime. Recently it's been happening while I'm on the machine. Thinking about the last couple of times it happened I was playing a pretty graphic intensive game (Far Cry). Happened in both XP and 2K after about 3 mins of playing. The vid card is the oldest component in this box. Otherwise it's happened at longer intervals while I'm just using the machine normally.
As far as stripping everything out there really isn't much to do there. Most everything is on the mobo in this box. The vid card is the only thing in any of the slots.
Even though the power suppy may be new, they still can fail. Now if you look at the distribution of the molex connector, they usually run in 2-3 channels from the source of the power suppy. try to hook up on hard drive and one disk drive(cd-dvd)drive to one channel of power from the power suppy, and use the other channel to hook up the secondary hard drive and the fans. After distibuting the power propery inside you case, close it up and now lets look out-side the box. MAke sure your using a surge protector, and if you are try to have and outlet just for the computer. To futher prevent problems attach a small APC UPS to the pc to stabalize power. Most of the random lock ups are caused by non-stable power to the PC.
You say that the video card is the oldest item in the box and everything else is onboard, which might mean there is onboard video?

If there is onboard video, try removing the video card and setting the MB up to use it's own graphics chip. It might not be as good for playing certain games, but if it proves the problem sits with the video card, you can go out and replace knowing you are not wasting your money.

If there is no onboard graphics, then try the video card in another slot. This will eliminate a badly seated graphics card and also a poor connection within the slot.
Mike -  I ran the mem test and let it run overnight. When I looked at the screen this morning the test had stopped and it said "Unexpected interrupt - Halting". I'm not really sure how to interpret the info on the screen but it said Pass: 17 Errors: 6435751. In addition when I rebooted it said I had a CMOS checksum error which I''ve never had before.
Another note - I just rebooted and the checksum error has disappeared.
Your ram has failed now you just need to find out what one. If you have more then one stick of ram.
Do this by running the test on each stick one at a time.
The checksum error will pop up when the expected ram count on the previous POST (power on self test) has changed.
Your ram has failed now you just need to find out what one. If you have more then one stick of ram.
Do this by running the test on each stick one at a time.
The checksum error will pop up when the expected ram count on the previous POST (power on self test) has changed.
Sorry for the double post the server went goffy or my pc did?
I only have 1 512 dimm so that narrows it down...;-). So the "Unexpected Interrupt Halting" was caused by the ram failing and not anything else?
Yes your Ram returend a value that was not what was expected.
It could be caused by a bad memory controller on the mother board.
But most likely is caused by bad ram.
Every problem ( bar one ) like this I have seen has been caused by HEAT.
To check for this - remove cover - get a really large fan ( a person fan not a pc fan)
Use pc with fan blowing cold air onto the pc - don't catch a cold from the draft :)

If all is well then get another PC fan and install.


P.S the bar one time was bad cache memory.
Snowguy - Bought a new 512 Dimm installed it and have the same problems. I ran the mem test on it and it also fails. I'm also getting random blue screens now.
Could be a bad memory controller on the mother board or just a bad mem slot.
Try it in another slot. Also check the memory settings in the bios set to auto or by spd see if that will help.
Do you have another system or a friends system you can check the memory in?
Tried it different slots already. No difference. Are there any viruses out there that would cause this behavior?
Have you checked the BIOS settings as Snowguy suggested?
I had a pc that would only run if the memory was under clocked even with good brand name ram.
It was pc133 but would only run if set to 100mhz. Dont know why tried alot of diferent moduels in the board and never could get it to run at 133mhz without failing.
Strange thing is though, this machine has been running flawlessly for about 4 months. This just seemed to come out of the blue. I know that's what everyone says but I can't think of anything that I might have done to cause this. The memory settings in the bios are set to auto and tried by spd. I left it off all night to make sure I wasn't having a heat issue. First boot this morning I got a blue screen that said I had a page fault in an unpaged area...any ideas on that? Rebooted and it locked up during XP loading. Rebooted again and went into 2K this time. So far so good, but it won't last long I'm sure.
Another common affliction that comes out of the blue is a failing power supply - it doesn't require too much expense to check, and it sometimes generates red herrings elsewhere.
You asked if a virus could cause this - answer yes.
As a former Network Manager the below routine is how I would check this.

Make sure you have
(1) virus checker installed and latestest updates. eg mcafee
(2) spyware detector software and latest updates eg adaware
(3) firewall software eg Zone Alarm latest version

run netstat -an looking for unusual open ports
Run msconfig (or startupCPL) and uncheck everything - except stuff you have to have.
I use
Check IE settings and restore defaults. I always use blank for home page.
Start ie6 and reset security and advanced stuff to defaults - high security
With Zone Alarm or equivalent. Set to disable all traffic.
Disconnect from network - remove cable
Boot into safe mode - no networking
Do your virus scan
Do your adaware spybot etc
Zone alarm will alert you if PC is trying to communicate with the outside world. If so find out why.
KEY to all this is to be in SAFE mode / NETWORK unplugged.

It is also possible that the swapfile is corrupt - resize to recreate.

Hope this helps.
ok everyone, problem solved. The errors and blue screens were so random that nothing was making sense so it made me think it might just be electrical. As I opened the case for a second time I saw the shielded cords that came with the case that were for hooking up front panel usb, firewire and sound. Because the cords that came with the mobo and the ones that came with the case were different connections I had a few mismatches so I just rolled up the cords and let them lay in the case. I thought that maybe something on one of those cords might be touching the case body somewhere. I removed all the cords that went to the front panel (I never have used those connectors anyway) totally from the case. Rebooted and I haven't had the problem again. I guess I really don't know exactly what was causing it but it's purring like a kitten again (with 1 gig of ram now).
In any case thank you all very much of your time and help. I know these kinds of problems are the most difficult and tedious to troubleshoot.  In all my years of computing I've never found a resource as helpful as this one. It's every bit worth the money. I wish I could divide the points up among everyone just for making me think but I don't think that's possible.
Again thanks for the help!
Since you solved the problem youself, you can post a note to that effect in Community Support with a link to this question and get your points refunded.
I have a premium subscription.
In that case, you can request that this question be closed and no points awarded.
Do I request that here or somewhere else?
Post a note in Community Support with a link to this question - the moderators pay attention to that area.
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